Eoessa Sakndenberg (sometime before 1503)

Vindictus Veridian (sometime before 1703)

1703

The Wizarding World of Harry Potter

Dilys Derwent (1741-1768)

1741 - 1768

Unidentified Professor (1790s)

1790

"Well, the Heads of the participating schools are always on the panel, because all three of them were injured during the Tournament of 1792, when a cockatrice the champions were supposed to be catching went on the rampage. It's all in Hogwarts, A History."
—Hermione Granger

Eupraxia Mole (1870's)

1876

Professor Eupraxia Mole was Headmistress of Hogwarts School of Witchcraft and Wizardry in the 1870s.[1]
In 1876, caretaker Rancorous Carpe devised an "elaborate trap" in an effort to remove Peeves, the resident Poltergeist, from the Castle — comprised of a bait of assortment of weapons and a vast enchanted bell jar, reinforced by various Containment Charms, which he intended to drop over the poltergeist once he was in place. This did not go as planned, as Peeves easily broke through the bell jar and was left armed with several cutlasses, crossbows, a blunderbuss and a miniature cannon. The Castle had to be evacuated for three days as Peeves amused himself by firing randomly and threatening the students with death.

Headmistress Mole agreed to sign a contract with Peeves, so that he relinquished from the weapons in exchange for additional privileges (a once-weekly swim in the boys' toilets on the ground floor, first refusal on stale bread from the kitchen for throwing purposes, and a new custom-made hat by Madame Bonhabille).

Pottermore

Phineas Nigellus Black (sometime in the late 19th century to before 1926)

1880 - 1925

Professor Phineas Nigellus Black (1847 – 1925) was a pure-blood wizard, possibly the son of Cygnus and Ella Black, and brother of Sirius, Elladora and Isla Black. He is the ancestor of many wizards in Britain. He attended Hogwarts School of Witchcraft and Wizardry and was sorted into Slytherin house; he later became Headmaster of the school and was said to be the least popular headmaster Hogwarts ever had. After he died in 1925, his portrait hangs in the Headmaster's office along with the portraits of the other former headmasters, and sometimes offers advice to the current headmaster.

Black family tree
Harry Potter and the Order of the Phoenix
Harry Potter and the Order of the Phoenix (film)

Armando Dippet (early 20th century-1956)

1900 - 1956

Professor Armando Dippet (October, 1637—late 1992) was Headmaster of Hogwarts School of Witchcraft and Wizardry, and the predecessor of Albus Dumbledore in the post. He was a "nearly bald and a somewhat feeble" man in his elderly years.
Dippet served as Headmaster in the 1940s at least. It was during his tenure that the Chamber of Secrets was first opened by Tom Riddle since its creation by Salazar Slytherin in around A.D. 993. Unknowingly, Dippet was indirectly responsible for the end of the attacks by telling Riddle that the school would have to be closed if said attacks continued. Dippet was also responsible for the expulsion of Rubeus Hagrid after Riddle framed him with the attacks.

Following his retirement, Dippet was accused of the Flying Ford Anglia incident in 1992. He died before December of the same year, and, ever since, his portrait hangs in the Headmaster's office. He is featured on a Chocolate Frog Card.

Newton Scamander (sometime in the early 20th century)

Albus Dumbledore (1956-1997)

(Suspended in 1993, later reinstated; assumed to have been sacked in 1996 after escaping a Ministry attempt to arrest him, reinstated later that year)

Minerva McGonagall (Acting) (1993)

1993

Dolores Umbridge (1996)

1996

Dolores Umbridge (1996) (Note: though Umbridge was proclaimed headmistress, she was not acknowledged as such by the headmaster's office, which shut her out for the remainder of the year. In addition, her portrait does not hang in the headmaster's office.)